What factors are responsible for the movement of solutes and water in and out of capillaries?

Blood pressure and diffusion

12 of 60

1- When the blood reaches the arterial end of a capillary it is ___ under pressure, the ___ pressure forces fluid from blood through capillary walls into spaces between cells

High and hydrostatic

13 of 60

2 - The outward flow is opposed by the reduced ___ of the blood, created by the presence of the ___ proteins

Water potential and plasma

14 of 60

3 - The hydrostatic pressure of the blood is greater than the ___ forces, so there is a net flow of water and solutes ___ of the blood

Osmotic and out

15 of 60

4 - At the arterial end of the capilary bed the diffusion gradient for solutes e.g. glucose, favours movement from the capillaries to tissue fluid, because ___

These substances are being used during cell metabolism

16 of 60

5 - At the venous end of the capillary bed the blood pressure is __ and water passes into capillaries by __, reduced water potential of blood created by ___ causes a net flow of water

Lower, osmosis and presence of plasma proteins

17 of 60

6 - At the venous end tissue fluid picks up __ and other excretory substances, some of this fluid goes back into capillaries but some drains into lymphatic system and its returned to the __ via the thoratic duct, which empties into a vein near heart

Venous system and carbon dioxide

18 of 60

What is the partial pressure of oxygen?

A measure of the oxygen concentration, the greater the concentration of dissolved oxygen tge higher its partial pressure

19 of 60

*30 Explain the significance of the difference between the oxygen dissociation curve of a foetus and the mother

It is more to left/combines more readily with oxygen, higher affinity for oxygen so takes up more oxygen from mums haemoglobin

20 of 60

Where is the foetal haemoglobin dissociation curve compared to the adult?

To the left

21 of 60

Does foetal haemoglobin have a higher or lower affinity for oxygen?

A higher/greater affinity for oxygen

22 of 60

What does the xylem transport?

Water and Mineral salts

23 of 60

What does the phloem transport?

Sugars and amino acids

24 of 60

Name the four different types of cells that make up the xylem?

Vessels, tracheids, fibres and xylem parenchyma

25 of 60

What is special about the vessels and tracheids in the xylem?

They are dead cells because lignin has been deposited on the cellulose cell walls making them impermeable to water and solutes, also provides strength and support

26 of 60

What is the region of greatest uptake in the root?

The root hair

27 of 60

Why does the soil water have higher water potential?

Because it contains mineral salts

28 of 60

Why does water enter the root hair?

Due to a low water potential in vacuole, causes water to enter down a water potential gradient by osmosis in one of three ways

29 of 60

Name the three ways in which water can travel along the cells of the cortex or the root?

- The apoplast - through the cell wall - The symplast - through the cytoplasm and plasmodesmata - The vacuolar pathway - from vacuole to vacuole

30 of 60

*35 State two functions of xylem

Support and transport of water

31 of 60

*36 Describe how water enters a root hair cell

Soil solution has high wp, root hair cells have low wp so water moves in by osmisis

32 of 60

Where is the xylem found?

In the center of the root

33 of 60

What is the xylem surrounded by?

A single layer of cells called the endodermis

34 of 60

What is the Casparian strip?

The endodermin impregnated with a waxy material called suberin

35 of 60

Which pathway is the only way water can pass the endodermis to the xylem?

The symplast pathway

36 of 60

*37 Explain why water passing along the apoplast pathway has to be re-routed when it reaches the endodermis

Endodermal cell has Casparian strip that prevents the passage of water

37 of 60

*38 Suggest the effect of a respiratory inhibitor on mineral uptake

Reduced or stopped as it is an energy requiring process

38 of 60

How are minerals absorbed to the root hairs?

By active transport

39 of 60

Which pathway do minerals use when absorbed?

The apoplast pathway

40 of 60

What happens when minerals reach the endodermis/Casparian strip?

Ions enter the cytoplasm of the cell where they can be diffused or actively transported to the xylem

41 of 60

In which form does nitrogen enter the plant?

Nitrate ions or ammonium ions

42 of 60

What is cohesion?

Water molecules tend to stick together

43 of 60

What is adhesion?

The water molecules stick to the walls of the xylem

44 of 60

What is capillarity ?

The tendency for water to rise in narrow tubes

45 of 60

What are the three main forces involved in water transport from root to leaf?

Root pressure, transpiration and capillarity

46 of 60

What is used to measure the rate of transpiration?

A potometer

47 of 60

How will an increased temperature affect the rate of transpiration?

Increases

48 of 60

How will a decreased temperature affect the rate of transpiration?

Decreases

49 of 60

How will a higher humidity affect the rate of transpiratiin?

Decrease

50 of 60

How will a lower humidity affect the rate of tranpiration?

Increase

51 of 60

How does lack of movement in the air affect the rate of transpiration?

Decreases

52 of 60

How does increased movement in the air affect the rate of tranpiration?